Ferrite Toroid, type 43 material. This model of toroid has been found by various hams to be a good choice for ununs for EFHW antennas, for an average power of up to about 40-50W.
Outside Diameter= 1.54 in / 39.1 mm +/- 0.75 mm
Inside Diameter = 0.66 in / 16.75 mm +/- 0.50 mm
Height = 0.875 in / 22.2 mm +/- 0.80 mm
- "Building an UNUN for an EFHW Antenna" article by Mike Dunstan G8GYW, in Practical Wireless October 2023
- https://owenduffy.net/blog/?p=21901 , https://owenduffy.net/blog/?p=23089 , plus various other articles that can be found by searching for 2643251002 on Owen's website